TextRun

Remarks

A run is one face, and a line is a list of them. See TextLine: a string whose characters are not all in one font becomes several runs, and so would a rich text span carrying its own size. Everything on this type is about the one face, so a consumer that reaches for Font or Scale is asking a question only a run can answer — the line is where a mixed-font width or caret lives, because those can only be composed in pixels.

⚠ One line. Nothing here breaks a paragraph across lines, so a string wider than its element overflows it rather than wrapping — the measure function ignores the width it is offered. Vixen.Ui.Text already has the UAX#14 line breaker this needs and wrapping is the next piece of text work rather than a missing consideration; said here so that a long label overflowing reads as a known edge rather than as a layout bug.

The size is carried alongside the shaping rather than baked into it, because the shaping is shared: the cache returns the same ShapedText for the same string in the same font whatever size it is drawn at, and this is the per-element view of it.

Fields and properties (11)

• public FontFace Font

  The face it was shaped with.

• public ShapedText Shaped

  The glyphs, in design units.

• public float Size

  The font size in pixels — what an em on this element measures.

• public float Tracking

  letter-spacing in pixels, added after every typographic character. Zero for the overwhelming majority of text, and the code below is written so that zero costs nothing.

• public float Leading

  The computed line-height in pixels, or NaN for the font's own recommendation. NaN rather than zero, because zero is a line height somebody might mean.

• public int Start

  Where this run's text begins in the element's, as a UTF-16 index. Zero for a line that is one run, and what lets a caret index reach the run it belongs to.

• public float Scale

  What multiplies a design unit to give a pixel.

• public int Clusters

  How many typographic characters the line has, for tracking to be added between.

• public float Width

  How wide the line is.

• public float Height

  How tall one line of it is.

• public float Baseline

  How far below the top of the line the baseline sits.

Methods (4)

• public TextRun(FontFace Font, ShapedText Shaped, float Size, float Tracking = 0, float Leading = NaN, int Start = 0)

  One stretch of an element's text: one face, shaped and measured at one size.

• public float CaretOffset(int index)

  How far along the run a caret index sits, in pixels.

• public int CaretIndexAt(float x)

  Which caret index a distance from the run's start lands on.

• public void Place(List<PositionedGlyph> into, float penX = 0)

  Places every glyph relative to the start of the line.

Used by (6)

• DrawListBuilderVixen.Ui
• FontFallbackTestsVixen.Ui.Tests
• FontRegistryTestsVixen.Ui.Tests
• TextLineVixen.Ui
• TextTestsVixen.Ui.Tests
• UiElementVixen.Ui